Other posibilities:

Coordination:

Every martial art will increase your coordination. Some more, and some less. Karate may not improve your coordination as much as Capoeira, but they both make you stronger and flexible in their own way. What’s important is that you pick something where you enjoy the trainer, the people and the art itself; otherwise you’ll end up quitting.Friends
You’d be amazed at how friendly the people are. This also depends on where and what you train. The more aggressive arts will obviously attract a different group than something softer.
As you try different arts, you’ll quickly see if it’s right for you. I personally love practical arts, which means I can use it in real life. Luckily, I’ve never needed to do that, because I’m a pretty friendly and easy-going guy.

Humbleness
A martial art with a good teacher can transform the way you think. You may go in with one mindset and come out a completely different person. Now, I’m not saying this will happen instantly, but definitely over time. Many martial arts are considered “dangerous”, so many kids are told to stay away from them. It isn’t the art itself that is dangerous, but how it is taught. Always look at what values the teacher has. Is he humble and friendly? Or does he use a more “old-school” way of teaching? Use common sense to pick a good teacher. Listen to your intuition. If there’s any common trait I’ve observed in good teachers, it’s humbleness, and this has definitely rubbed off on me.

Discipline
You will go through periods where you absolutely do not feel like going to class. It will feel tough and nothing seems to work when you do train.
Discipline is a cornerstone in all of the old arts, and something that is required in whatever you do. If you can make it past the six month mark, you will be ahead of the large majority of people.

Mindset
One of the biggest benefits I’ve noticed from martial arts is the psychological part. When you start out, you’ll probably be scared of putting your heart into what you’re doing.
We aren’t used to attacking and defending. It’s a whole new playing field, and it opens up your mind. Once you allow yourself to get in the zone and improvise, something in your reality changes.